1. Field of the Invention
The present invention relates to an electrode for radiofrequency tissue ablation which can coagulate and necrotize a tissue by radiofrequency electric energy, and more particularly, to an electrode for radiofrequency tissue ablation which can coagulate and necrotize a target part of a tissue by sensing a temperature of the tissue.
2. Description of Related Art
There has been suggested a method for coagulating or ablating a target tissue with radiofrequency energy by inserting a long hollow tube type electrode into the tissue. Here, a radiofrequency output is transmitted to the tissue to heat the tissue, so that the tissue and blood vessel can be coagulated by more or less complicated biochemical equipment. Such a process is carried out by coagulation of a cell (including tissue, blood vessel and blood) by heat distortion of protein in the cell over about 55° C.
However, the tissue and blood are excessively coagulated and carbonized near the electrode for radiofrequency tissue ablation. Such a carbonized tissue is operated as an insulator interrupting expansion of a tissue coagulation area. In order to solve the above problem, tissues can be coagulated and necrotized in a wide area by lowering a temperature of peripheral tissues by circulating a coolant saline solution in the electrode or externally ejecting the saline solution. In addition, the tissues can be coagulated and necrotized in a wide area by circulating a coolant saline solution and externally ejecting some of the saline solution at the same time.
FIG. 1 is a side-sectional view illustrating a conventional electrode for radiofrequency tissue ablation.
In detail, as illustrated in FIG. 1, the conventional electrode for radiofrequency tissue ablation includes a sharp closed end 10 inserted into a tissue, for generating radiofrequency energy, and a hollow electrode 20 connected to the closed end 10. An insulation coating 24 is coated on the outer circumference of the hollow electrode 20 except for the part connected to the closed end 10. A control unit (not shown) is installed to generate radiofrequency electric energy in the closed end 10 by supplying an output to the closed end 10 and the hollow electrode 20. A hollow refrigerant tube 30 is installed in the hollow electrode 20 with a predetermined gap from the inner circumference of the hollow electrode 20. Cooling water flowing into the refrigerant tube 30 is discharged between the refrigerant tube 30 and the hollow electrode 20 after cooling the closed end 10.
If necessary, a hole 20h is formed on the part of the hollow electrode 20 adjacent to the closed end 10, so that some of the cooling water can be directly injected into the tissue to prevent carbonization of the tissue and expand the electrode area to efficiently coagulate the tissue.
A temperature sensor 22 is installed on the outer circumference of the hollow electrode 20 adjacent to the closed end 10, for sensing a temperature of the closed end 10. According to the sensed temperature, the control unit controls the closed end 10 to generate radiofrequency electric energy for a predetermined time by adjusting the output. Here, the tissue is maintained over a predetermined temperature for a pre-determined time for complete coagulation and necrosis.
However, in the conventional electrode for radiofrequency tissue ablation, since the temperature sensor 22 is installed near the closed end 10 generating radiofrequency electric energy, the temperature sensor 20 can only sense the temperature of the closed end 10 and the temperature of the tissue adjacent to the closed end 10. It is thus difficult to coagulate and necrotize only a target part by maintaining a pre-determined temperature in an accurate ablation part.